EP0069973B1 - Transformer coil - Google Patents

Description

The invention relates to a transformer coil with a one-piece coil body made of insulating material with flanges formed on both ends and with a core bore, in the area of which a longitudinal rib is formed, with winding support points arranged on at least one coil flange, and with one arranged in the core bore, axially over the iron core extending beyond the coil flanges.

Such a transformer coil is already known from DE-B-1 539 679. There, a coil former made of plastic with an approximately rectangular winding cylinder is used, in which a sheet metal core with alternately connected iron sheets is inserted. The inner wall of the winding cylinder is provided with burr-like strips in order to achieve a press fit or tolerance compensation for the laminated core when the core sheets are inserted. However, such a transformer coil with a rectangular cross section cannot be used, for example, in rotationally symmetrical transformers, in particular in rotary transformers. In such applications, it is also desirable to widen the core outside the coil flanges in the radial direction in order to better close the iron circuit. In such a case, the core can neither be layered as a laminated core, nor can it be introduced in one piece into the coil former. In addition, in such a case the winding support points cannot be provided next to one another on the coil flange as in the known coil.

For such transformers, it was therefore customary either to isolate the core, which was provided in one piece with two iron flanges, only with paint on the surface, or to line it with insulating films and then to wind it without a coil former, or to apply plastic half-shells instead of this paint insulation. In both cases, it is difficult and expensive to safely isolate the iron core from the winding; In addition, apart from the loss of the winding space, the winding process is more difficult in terms of production technology, since winding bases, as are well known on other bobbins, are missing and the winding ends must therefore be tied off individually.

From DE-A-1 919 729 a rotationally symmetrical coil body with a round iron core for relays and the like is known. However, the full cross-section of the core is made of iron, so this construction cannot be considered for a rotary transformer. Measures are not specified there to accommodate a core with an enlarged cross section at both ends, nor could the coil former there be used for a rotor of a rotary transformer because of the winding support points arranged on the flange circumference.

DE-A-2 208 457 shows a winding body for transformers which, because of its rectangular cross section, is not suitable for a rotary transformer. In the case of a rotationally symmetrical core with iron flanges, the adjacent winding support points on the bobbin flange would also interfere.

US-A-4 166 265 generally shows a bobbin with winding support points which are arranged in the form of wires or pins in a flange. Because of the rectangular cross-section and because of the winding support points lying next to one another, this coil former would also be out of the question for a rotary transformer.

The object of the invention is to design a transformer coil of the type mentioned with a rotationally symmetrical and enlarged at the outer ends in cross-section, which is particularly suitable for use as a rotor of a rotary transformer, so that the manufacture and winding of the coil body and also the assembly of the core can be made simple and inexpensive.

• - daß der Eisenkern quer zu seiner Längsrichtung in zwei Kernteile unterteilt ist, welche in der Längsrichtung jeweils einen die Kernwandung vollständig durchtrennenden Schlitz und an ihrem aus dem Spulenkörper herausragenden Ende jeweils einen angeformten Eisenflansch aufweisen,
• - daß die Längsrippe des Spulenkörpers in die Schlitze beider Kernteile eingreift und
• - daß die Wickelstützpunkte am Ende der Längsrippe angeordnet sind.

According to the invention, this object is achieved by

• that the iron core is divided transversely to its longitudinal direction into two core parts, each of which has a slot in the longitudinal direction that completely cuts through the core wall and an integrally formed iron flange on its end protruding from the coil former,
• - That the longitudinal rib of the coil body engages in the slots of both core parts and
• - That the winding support points are arranged at the end of the longitudinal rib.

The inventive design of a bobbin makes it possible, for example, to insert a two-part slotted, sleeve-shaped core from the two ends into the bobbin and to align the slots in each case on the longitudinal rib of the bobbin. As a result of the arrangement of winding support points in the extension of these longitudinal ribs, these also come into the slot of the coil core when the core outside the coil is enlarged in a disk shape over the entire radius of the coil flange. According to the subclaims, these winding support points can be provided on a rib-shaped extension of the longitudinal rib, this extension coming to rest in a radial recess in the core, which is expanded outside the coil to form an iron flange. In this case, two or more winding support points on the coil flange are expediently arranged one above the other in the radial direction in order to obtain good insulation for the applied winding ends even in a narrow slot in the iron flange.

The winding bases themselves can be on be formed on the coil flange or on the rib-shaped extension in the form of two hook-shaped lugs. For winding, it is advantageous if the winding axes of the two winding support points form such an angle with respect to one another that the winding movement of the wire on one winding support point does not touch the other winding support point. The angle required for this can be determined in individual cases on the basis of the size relationships of the coil flange and the winding support points.

To accommodate the winding ends, the winding support points have grooves which are recessed at least on one side, as a result of which the distance between the wound winding ends and a slotted iron core is also increased. It would also be beneficial to fix the winding ends in recessed grooves all around, but in general the one-sided groove is easier to manufacture using tools. Furthermore, it is expedient that the coil flange carrying the winding support points is radially slotted next to these winding support points and thus enables the wire to enter the winding start.

The winding support points can also be embedded in the form of wires in the end of the longitudinal rib or in the extension thereof. In addition, in a further development of the invention, further metal inserts can also be embedded in the longitudinal rib or inserted subsequently, for example in order to achieve a phase shift in a transformer.

• Fig. 1 bis 3 einen erfindungsgemäß gestalteten Spulenkörper in drei Ansichten,
• Fig. 4 und 5 die Anwendung des Spulenkörpers von Fig. 1 bis 3 in einem Transformator,
• Fig. 6 bis 10 weitere Ausgestaltungsmöglichkeiten des Spulenkörpers in schematischer Darstellung.

The invention is explained in more detail below using exemplary embodiments with reference to the drawing. It shows

• 1 to 3 an inventive coil body in three views,
• 4 and 5, the application of the bobbin of Fig. 1 to 3 in a transformer,
• Fig. 6 to 10 further design options of the coil body in a schematic representation.

1 to 3 show a bobbin 1, which preferably consists of elastic, temperature-resistant, thermoplastic insulating material. The winding 3, which is only indicated, is applied to the coil tube 2 and is delimited by the flanges 4 and 5 at both ends of the coil body. The core bore 6 serves to receive an iron core, as is shown, for example, in FIG. 4. To align a slotted, possibly multi-part core, the bobbin has a longitudinal rib 7 in the bore 6, which extends beyond the flange 4 into a rib-shaped extension 8 and forms two hook-shaped winding support points 9 and 10. This makes it possible to use a core with an iron flange overlapping the coil flange 4 if it has a slot for receiving the rib-shaped extension 8. This slot can be relatively narrow, since the winding support points 9 and 10 are arranged radially one above the other in a line. This means that coils that are to accommodate a core with iron flanges can also be wound quickly and inexpensively, since very thin untwisted winding ends can be wound quickly at the winding support points 9 and 10, and the binding and knotting of the winding ends previously required in such coils is eliminated. In addition, due to the lack of the tying knots, there is a considerable gain in changing space.

The coil flange 4 has a slot 12 for the wire entry of the winding start 11, the slot edges are also rounded, and an inlet bevel 13 is formed on the coil flange with a small angle y. The winding end 14 is in turn guided through the slot 12 of the coil flange 4 onto the winding base 10. Both winding support points 9 and 10 are inclined with respect to one another in their winding axis in such a way that when winding onto one support point the other does not hinder the looping movement of the wire. For this purpose, the angles of the winding plane α at the winding base 9 and 8 at the winding base 10 are chosen to be correspondingly large with respect to the end plane of the coil former, taking into account the distances between these two winding bases and the other dimensions.

The hook ends of the winding support points 9 and 10 secure the winding ends against slipping. For an even better fixation of the coil ends and also to increase the insulation strength by increasing the air gaps to the metal parts, these winding support points continue to have grooves 15 on one side, so that the applied winding ends can lie flush with the lateral surface of the winding support points. The winding support points could also be provided with grooves on all sides, but this would result in a more complicated tool design for the manufacture of the coil former.

The coil flanges 4 and 5 are on the one hand tapered outwards for reasons of strength and shape, and on the other hand to facilitate mechanized winding and are rounded on the inside edges.

4 and 5 show the application of the coil former from FIGS. 1 to 3 in a transformer, as is used, for example, in a rotary ring-less resolver. In this case, a two-part core is arranged in the coil former 1 with the winding 2, the two parts 16 and 17 of which are each inserted into the core bore from the coil ends. In the area of the coil tube, these core halves 16 and 17 are each sleeve-shaped and with their inner bore placed on a rotor shaft 18. At the coil ends, these core halves are each formed into iron flanges 19 and 20, which extend in the radial direction next to the coil flanges and each form air gaps 25 with respect to the iron core 21 of a stator coil 22 (bearings are not shown).

The core halves 16 and 17 including theirs Iron flanges 19 and 20 are continuously provided with a slot 23, by means of which they are aligned on the longitudinal rib 7 of the coil body 1. In the area of the rib-shaped extension 8 with the winding support points 9 and 10 (see FIG. 1), the slot 23 is expanded into a recess 24 in order to ensure a sufficient insulating distance from the wound winding ends of the coil 3.

6 to 10 show modified versions of the bobbin 1 in a schematic representation. 6 shows a bobbin 31 which has a chamber 33 in the longitudinal rib 32 which, for example, can accommodate short-circuiting pieces for phase shifting a transformer. Such metal parts can be subsequently inserted into the chamber 33 or embedded during the manufacture of the coil former. In this case, winding support points, which also serve as soldering support points, can be provided, for example, on the invisible side of the opposite coil flange 34.

FIG. 7 shows a coil former 41 with a longitudinal rib 42, in which two wire pieces 44 and 45 are embedded as winding support points in the region of the coil flange 43. In the bobbin 51 according to FIG. 8, the longitudinal rib 52 on the coil flange 53 has an extension 54 which also has embedded winding support points in the form of wires 55 and 56. In this case, the wires are arranged at an angle to one another such that the winding movement of the wire around one winding base does not hinder the other winding base.

Finally, FIGS. 10 and 10 show in a further modification a bobbin 61, the longitudinal rib 62 of which forms two webs 63 and 64. These webs in turn form a chamber for inserts, such as short-circuit pieces or other metal inserts. In Fig. 10, these webs 63 and 64 each have extensions 65 and 66 which extend along the coil flange 67 in the radial direction. This means that inserts that have been unwound can be guided in isolation up to the outer diameter of the coil flange.

Claims (10)

1. A transformer coil comprising in integral coil body (1) of insulating material having flanges (4, 5) formed on each end, and a core bore (6), in the region of which a longitudinal rib (7) is formed; winding supports (9, 10) arranged on at least one coil flange; and an iron core which arranged in the core bore (6) and extends axially beyond the coil flanges, characterised in

- that the iron core is divided transversely to its longitudinal direction into two core parts (16, 17) which, in the longitudinal direction, respectively have a slot (23) which completely divides the wall of the core and an attached flange (19, 20) at their ends which protrude beyond the coil body (1, 31, 41, 51, 61);

- that the longitudinal rib (7, 32, 42, 52, 62) of the coil body (1, 31, 41, 51, 61) engages into the slots (23) of the two core parts (16, 17); and

- that the winding supports (9, 10, 44, 45, 55, 56) are arranged at the end of the longitudinal rib (7, 32, 42, 52, 62).

2. A coil as clamed in Claim 1, characterised in that the winding supports (9, 10, 55, 56) are arranged on a rib-shaped extension (8, 54) of the longitudinal rib (7, 52) on the coil flange (4,53).

3. A coil as claimed in Claim 2, characterised in that two hook-shaped, mutually offset winding supports (9, 10) form an integral part of the extension (8).

4. A coil as claimed in Claim 2 or Claim 3, characterised in that the winding supports (9,10) are arranged in the radial direction so as to be displaced with respect to one another.

5. A coil as claimed in one of Claims 1 to 4, characterised in that the winding supports (9, 10) have their respective winding axes tilted opposite to one another relative to the end surface of the coil flange (4) by an angle (α,β) which is such that, as a result of the rolling movement of the winding ends (11, 14} on a respective one of the winding supports, the other winding support is not contacted.

6. A coil as claimed in one of Claims 3 to 5, characterised in that in order to accommodate and fix the winding ends in a form-locking fashion, the winding support (9, 10) are in each case provided with a groove (15) on one side.

7. A coil as claimed in one of Claim 1 to 6, characterised in that the coil flange (4) supporting the winding supports (9, 10) has a radial slot (12) beside the winding supports.

8. A coil as claimed in one of Claims 1, 2 or 4, characterised in that winding supports in the form of wires (44,45,55, 56) are embedded in the longitudinal rib (42), or the extension (54), as the case may be.

9. A coil as claimed in one of Claims 1 to 8, characterised in that metal inserts are embedded in the longitudinal rib (32).

10. A coil as claimed in one of Claims 1 to 9, characterised in that the longitudinal rib (32, 62) has at least one chamber (33) for housing slide-in components.

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